ERBB2 and breast cancer: Trastuzumab has been used as the first-line treatment in combination with chemotherapy such as docetaxel or paclitaxel in locally advanced or metastatic HER2-positive breast cancer, with response rates ranging between 50% and 80% [2, 7] and as the second-line or later treatment in combination with different cytotoxic agents [ORR, 20%-68%] [8–16].